The present invention relates to a method of displaying a color picture image and an apparatus therefor, in which a picture image is displayed on a picture screen by scanning rasters.
In the case where it is intended to display a color picture image in a CRT display device or the like in the same manner as in the case of a monochromatic picture image, there is a problem that the memory capacity increases in comparison with the case of display of monochromatic picture images because display memories are required corresponding to the respective colors.
As an example of prior art in which increase in memory capacity is avoided, a method disclosed in Japanese Patent Unexamined Publication No. 23519/1980 is known. In this method, a memory having the same number of bits as that of dots (the number of picture elements of a monochromatic picture image) on one picture screen is divided into four sections and the three color picture image information components R (red), G (green), and B (blue) are respectively written into the areas of the three of the four memory sections. The information components R, G, and B relatively in the same addresses counted from the respective head addresses are simultaneously read out from the divisional memory sections, and a set of read-out information components R, G and B are displayed at four dots constituting a corresponding color picture element on the picture screen of the CRT display device. Thus, although resolution is deteriorated, a color picture image can be displayed by using a memory with a capacity for one picture scene of a monochromatic picture image.
In such a method, however, there are such problems that it is impossible to use a highly densely integrated memory because the memory is divided into a plurality of memory sections, and that the logic controlling the memory reading-out operation is complicated because information components relatively in the same addresses counted from the respective head addresses are simultaneously read out from the divisional memory sections.